Speed control for sheet handling apparatus

ABSTRACT

A sheet handling apparatus is disclosed having a first sheet feeding means for advancing a sheet along a sheet path, a second sheet feeding means for feeding the sheet along a continuation of the sheet path, driving means for driving the first sheet feeding means independently of the second sheet feeding means and for common drive of the first and second sheet feeding means, and a drive controller arranged to control said driving means to enable a sheet to be driven along the sheet path from the first sheet feeding means to the second sheet feeding means whilst the second sheet feeding means remains undriven and to enable continued feeding of the sheet by both sheet feeding means.

FIELD OF THE INVENTION

This invention relates to sheet handling apparatus and is applicable toan apparatus and method for processing of elongate elements or articles,and in particular to an apparatus and method for selectively performinga plurality of operations on each of a number of different sheet orbooklet elements, as well as envelopes.

BACKGROUND OF THE INVENTION

It is well known to provide a machine for successively performingseveral operations on various sheet elements. For example, operations onan envelope might include flapping, inserting, moistening and sealing,whilst operations on one or more sheets might include collating, foldingand inserting into an envelope. It is further known to provide a machinewhich collates several sheets of paper into a bundle, folds the bundle,places an insert, such as a leaflet or booklet into the bundle, providesan envelope which is held open, inserts the folded sheets into theenvelope, moistens the envelope and seals it, before ejecting theenvelope into a receiving tray or bin. Each of these operations isdistinct and requires a separate and unique processing region within themachine in order to successfully and repeatably carry out the requiredoperation on the respective element. As a result, folder/insertermachines of the type described hereinbefore are typically large andcomplicated to program.

Recently, there have been moves towards reducing the size of such folderinserter machines in order to make them more accessible to smallerbusinesses, such as SOHO (small office/home office) operations. In orderto be successful in this environment, the folder/inserter must occupy asmall footprint (i.e. the area of floor/desk-surface occupied), performreliably, and be easy to control without requiring specialist training.

GB-A-2380157 discloses a small office folder/inserter having two trays,and for storing sheets to be folded and the other for storing inserts tobe inserted into the sheets. One location is specified for folding saidsheets, another location for placing the insert into the folded sheets,and a further location for inserting the folded bundle into an envelope.The machine further comprises a location for storing envelopes, meansfor opening said envelopes and holding the envelopes open to receive thefolded bundle at the inserting location, a section for moistening theflap of the envelope and a section for closing the flap of the envelopeto seal it and ejecting the envelope to a receiving tray. Because of thesmall size and compactness of the machine, it is suitable for performingonly a limited number of cycles in a given time period, i.e. it does nothave a very high-volume throughput. Further, such machines can lackversatility, since they are suitable only for performing the respectivefeeding, folding, inserting, envelope opening, envelope moistening andsealing operations on a limited range of sizes of sheets/inserts.

Large organisations, such as banks, telephone companies, supermarketchains and the government, for example, are often required to produceextremely large throughputs of specifically-addressed mail to a regionalor national audience. Machines capable of producing the high volumesrequired, whilst simultaneously accurately ensuring that the correctcontent is sent to the individual recipients, are typically very large,often occupying an entire warehouse. By contrast, existing small officeequipment is typically capable of producing mailshots for a few hundredto one or two thousand addressees.

Demand, therefore, exists for a machine of intermediate productioncapacity, typically for small to regional businesses, which does notoccupy a vast quantity of the available office space. Particularly inlarge cities, office space is charged at premium rates for each squaremetre. As such, the cost of running and maintaining a folder/inserterwill also comprise the cost of renting the office space which itoccupies.

SUMMARY OF THE INVENTION

For folder/inserter apparatuses intended for small and medium sizedbusinesses, it is at least desirable, if not necessary, for the machineto be able to accommodate a range of different materials. For example,it will be necessary to accommodate different thicknesses of sheetelement, as well as different sizes and numbers thereof. Similarly, anymaterials to be inserted within a folded package might range from acompliments slip to an entire booklet, including inserts ofunconventional size or shape. It is also advantageous for such machinesto be able to accommodate different sizes of envelopes, such as A4 andA5, depending on the material to be inserted thereinto.

When accumulating a document in a mail creation machine it is desirablefor the delivery rollers and the receiving rollers/belt to be veryclosely matched in speed. This prevents the paper being stretched if thefeed rolls are too slow or crumpled if too fast. Driving with twoindependent motors requires very accurate control systems, so the usualmethod of matching the speed is to mechanically link the two and haveone motor for both. This however makes it difficult to stop one sheet inthe accumulator and wait for the next to arrive. This invention linksthe two drives via an overrun clutch allowing the delivery motor to feedindependently of the receiving motor whilst maintaining accurate speedmatching when the receiving motor is on.

According to one aspect of the present invention, there is provided asheet handling apparatus comprising: a first sheet feeding means foradvancing a sheet along a sheet path; a second sheet feeding means forfeeding the sheet along a continuation of the sheet path; means fordriving the first sheet feeding means independently of the second sheetfeeding means and for common drive of the first and second sheet feedingmeans; and a drive controller arranged to control said driving means toenable a sheet to be driven along the sheet path from the first sheetfeeding means to the second sheet feeding means whilst the second sheetfeeding means remains undriven and to enable continued feeding of thesheet by both sheet feeding means.

According to a second aspect of the invention, there is provided amethod of feeding sheets in which a sheet is fed by first feeding meansto a second feeding means whilst the second driving means remainsundriven and the sheet is further advanced by both the first and secondfeeding means set at a specific ratio therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how the same maybe carried into effect, reference will now be made, by way of example,to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a sheet handling apparatus detailingthe different machine sections;

FIG. 2 is a cross-sectional view of a sheet feeder deskew mechanism;

FIG. 3 is a cross-sectional view showing the sheet feeder collationsection;

FIG. 4 is a schematic view of an accumulator according to an embodimentof the present invention;

FIG. 5 is a cross-sectional view showing the accumulator installed in asheet handling apparatus;

FIG. 6 is a cross-sectional view showing the sheet folding section; and

FIG. 7 shows a speed compensation mechanism according to one embodimentof the invention.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the drawings, like numerals are used to identify likecomponents.

FIG. 1 shows a folder/inserter apparatus 1000 embodying the presentinvention. This embodiment is exemplary only, and is used to highlightand explain the inventive concept defined by the appended claim.

FIG. 1 shows a cross-sectional view of the folder/inserter apparatus1000 and schematically shows various sections of the machine. Thefolder/inserter apparatus 1000 comprises a sheet feeder sectionincluding sheet feeders 1, 2, 3 and 4, from which sheets are fed into acollation section 100 where they are collated into an ordered paperstream. The paper stream is then fed along a sheet feed path whichmerges with an inlet from a convenience feeder 200, which acts as analternative sheet feeder for certain documents. The sheets then passthrough an accumulator section 300 where they are grouped together as anordered and aligned package. From the accumulator, the sheets passthrough a sheet folder 500. Inserts fed from insert feeders 401 and 402are collated in an insert feeder collation section 450 and then fed intoa folded collation. An envelope is fed from an envelope feeder 600 alongan envelope transport path 650 to a flapper 700 where the envelope flapis opened and the mouth of the envelope held open at insertion section750 to receive the folded collation. The collation is inserted into theenvelope and the envelope is fed into a final section 800 where the gumon the envelope flap is moistened and the envelope sealed. The sealedenvelope is then ejected into a receiving tray or bin.

Referring now to FIG. 1 in more detail, there is shown an inlet sectionwhich includes four sheet feeders 1, 2, 3 and 4. Each of these sheetfeeders comprises a respective sheet feeder tray 5,6,7 or 8 into which astack of sheets may be placed. The sheets in each tray are fedindividually into a sheet feed path by respective sheet deskewmechanisms 50 which each act to separate a single sheet from the top ofa stack of sheets in the associated sheet feeder tray and to feed theseparated sheet into and along the sheet feed path. Four deskewmechanisms 50 are shown in FIG. 1, only one of which is identified byreference numeral 50 in FIG. 1. The other three deskew mechanisms areeither identical or equivalent to that labelled 50. Each of the sheetfeeder deskew mechanisms feeds into a common sheet feed path viarespective sheet feeding inlet paths P1, P2, P3 and P4. The conveniencefeeder 200 similarly feeds into the common sheet feed path. All inletsto the sheet feed path from the four sheet feeders and from theconvenience feeder 200 merge by a point T within the sheet feedercollation section 100. From the point T, the sheet feed path continuesas a single sheet feed path up to the folder station 500. The sheet feedpath passes first through the accumulator 300, where a plurality ofsheets may be brought together to form an aligned and ordered package.The sheet feed path then passes through the sheet folding section 500which produces a desired fold pattern in the accumulated document. Asshown on the righthand side of FIG. 1, a pair of insert feeders 401, 402are provided. Each insert feeder 401, 402 has a respective feeder tray411, 412 which holds a plurality of inserts to be inserted into thefolded collation. Each insert feeder further has an associated feederdevice 400 for feeding a single insert into the insert collation section450. Inserts fed into the insert collation section 450 are collatedtogether and then inserted into the main folded collation. On thelefthand side of FIG. 1 below the sheet feeders 1,2,3 and 4 is locatedthe envelope feeder 600. Envelope feeder 600 holds a plurality ofenvelopes which are fed along the envelope transport path 650 and intothe flapper mechanism 700. The flapper mechanism 700 opens the flap ofeach envelope and uses mechanical fingers to hold the mouth of theenvelope apart at insertion section 750 in order to allow the foldedsheets (and any inserts) to be projected into the envelope. Theenvelope, with inserted documents, then continues along the sheet feedpath to the final section 800 in which the gum on the envelope flap ismoistened and the flap is sealed. The sealed envelope is then ejectedfrom the folder/inserter apparatus 1000.

The operation of the folder/inserter apparatus is now considered in moredetail with reference to FIGS. 2 to 6.

Referring now to FIG. 2, the sheet feeder deskew mechanism 50 comprisesa separator roller 51 which applies a driving force to the uppermostsheet in a stack in the sheet feeder tray. The separator roller 51presses against a separator pad 52, normally in the form of a separatorstone. This separator stone 52 prevents more than one sheet at a timefrom being fed into the sheet feed path by the roller 51. The singlesheet removed from the sheet feeder tray by the separator roller 51 isthen driven towards a deskew roller pair 53 which is maintainedstationary. As the sheet engages the nip defined by the deskew rollerpair 53 it is caused to buckle (as illustrated at Z). This forces thelead edge of the sheet to align with the nip of the deskew roller pair53. The separator roller 51 is then stopped and the deskew roller pair53 operated to drive the sheet along the sheet feed path and into thesheet feeder collation section 100.

With reference to FIG. 3, each sheet fed from a sheet feeder 1,2,3 or 4or convenience feeder is received in the respective sheet feeding inletpath P1,P2, P3, P4 or P5 defined by guides G1 and G4 to G10. The sheetfeeding inlet paths merge into a single sheet feed path in the sheetfeeder collation section 100. Sheet feeding roller pairs 101, 102, 103and 104 are located along the sheet feed path for forcing the sheetsalong the sheet feed path.

In a typical sheet folding/inserting operation involving a four-pagedocument, referring also to FIG. 1, the first sheet feeder tray 5receives a stack of sheets corresponding to page 1 of the document, thesecond sheet feeder tray 6 receives a stack of sheets corresponding topage 2 of the document, the third sheet feeder tray 7 receives a stackof sheets corresponding to the page 3 of the document, whilst the fourthsheet feeder tray 8 receives a stack of sheets corresponding to page 4of the document. A single sheet is then fed sequentially from each ofthe first to fourth sheet feeders. The first sheet from the first sheetfeeder 1 passes into and along the sheet feeding inlet path P1 andpartially along the common sheet feed path. A sheet is then fed from thesecond sheet feeder 2 such that the leading edge of the second sheetpartially overlaps the trailing edge of the first fed sheet within thesheet feeder collation section 100. Similarly, the third sheet is fed sothat the leading edge of the third sheet partially overlaps the trailingedge of the second sheet, whilst the fourth sheet is fed so that itsleading edge partially overlaps the trailing edge of the third sheet.This forms a collation of the sheets along the sheet feed path in thesheet feeder collation section 100. The guides G1 to G10 defining thesheet feed path are configured and arranged to ensure that, as thesheets are sequentially fed into the sheet feed path and carried tooverlap as described above, they become correctly collated in theintended order.

Because the requirement is that the adjacent sheets in the sheetcollation only partially overlap at the leading and trailing edges, itis possible to drive the sheet collation along the sheet feed path athigh speed without requiring a complex control system to ensure thateach of the sheets is correctly aligned with those adjacent to it. Thisenables a high-volume throughput of mail packages to be achieved.

Referring now to FIGS. 4 and 5, the sheet collation is then driven fromthe collation section 100 into an accumulation section 300 comprising avertical accumulator 350. Here, as each sheet arrives in the accumulator350, it is gripped and forcibly advanced through the accumulator by apair of traction belts 351 running vertically and mutually parallel on asled 352. A plurality of spring-biased idler rollers 365 to 369 areprovided for each traction belt 351 to apply forces F1 to F5 to maintainthe most recently-arrived sheet in contact with the tractions belts 351.Each sheet fed into the accumulator 350 arrives at an accumulationchamber 364 defined on one side by a sled guide assembly SG includingthe sled 352 and the traction belts 351 and on the other side by a fixedguide assembly OG including fixed guide 353 and idler rollers 365 to367. The accumulation chamber 364 is substantially straight andvertical, such that the collation is accumulated into a vertical stackof sheets. At the bottom of the accumulation chamber 364 is anaccumulation gate 354 functioning as a stopping device. Each sheetentering the accumulator 350 is driven downwardly through theaccumulation chamber 364 towards the accumulation gate 354 by thetraction belts 351 until its leading edge comes into contact with theaccumulation gate 354. This causes the sheet leading edge to impinge onthe accumulation gate 354 and the sheet to become correctly alignedwithin the accumulation chamber 364. The sheet is then maintained withinthe accumulation chamber 364 and rests on the accumulation gate 354,whilst further driving of the traction belts causes slippage between thetraction belts 351 and the sheet. Thus, once the first sheet has beenstopped by the accumulation gate 354, the second and subsequent sheetsare consecutively driven into alignment with the first sheet by thetraction belts 351 driving each sheet in turn along the accumulationpath and against the accumulation gate 354 to form an ordered collation.When all of the sheets in the collation have been successfully groupedat the accumulation gate 354, the accumulation gate opens to allow thecollation to progress out from the accumulation chamber 364 along thecontinuation of the sheet feed path.

Referring now to FIG. 5, it can be seen that the accumulator comprisesthe fixed guide assembly OG, and movable sled guide assembly SG. Themovable guide assembly SG includes driving means in the form of the pairof traction belts 351. The fixed guide assembly OG includes idlerrollers 365 to 367 for pressing the sheets to be accumulated against thetraction belt 351 and rollers 361 to 363 for pressing the traction beltagainst the sheets to be accumulated. The movable guide assembly alsoincludes the sled 352 for assisting guidance of the sheets, orcollations of sheets, into an accumulated bundle whilst accommodating avariable thickness of accumulation. These features define a section ofsheet feed path which is substantially vertical and acts as theaccumulation chamber 364. In the embodiment shown, the means for drivingthe sheets downwardly towards the accumulation gate 354 is the pair oftraction belts 351, although any suitable system of belts and rollerscould be used. The present embodiment has two drive belt assemblieswhich each consist of one of the traction belts 351, a drive roller 355and a secondary tension roller 356 which holds the traction belt 351under tension, along with idler rollers 361, 362, 363 in the sled 352acting in opposition to the idler rollers 365 to 367 in the fixed guideassembly. The idler rollers 365 to 367 associated with the fixed guide353 could alternatively take the form of miniature drive belts biasedtowards the fixed idler rollers 361,362,363 in the sled, but preferablysprung idler rollers are biased towards the traction belts. Further,idler rollers 368 and 369 are mounted on a further guide componentpositioned above guide 353 (see FIG. 5). The idler rollers 365 to 369may be arranged to apply a force to the sheet which varies along thelength of the accumulation chamber 364 and around the drive rollers 355of the traction belt mechanisms 351. Such a variable traction force overthe length of the accumulation chamber, preferably ensuring a largerforce towards the bottom of the accumulation chamber, reduces the columnstrength of a sheet required to enable it to resist the frictionaldriving forces of the traction belts. In the present embodiment, thevaried force is achieved by using sprung idler rollers 365, 366 and 367,each of which is biased towards the traction belts 351 by a differentspring force, the spring force being largest for roller 367 and leastfor roller 365. The downward driving force is resisted at the bottom ofthe accumulator by the accumulation gate 354, but it is important thatthe traction forces from the driving means do not cause the individualsheets to buckle or concertina.

In traditional accumulators, the accumulated collation must bemechanically forced in order to propel it further along the sheet feedpath. Because contact can be achieved only with the front and rearsheets at any time, the acceleration given to the accumulated collationmust be limited in order to ensure that adjacent sheets do not sliderelative to one another, thereby spreading apart the accumulatedcollation. As a result of the vertical orientation of the accumulationpath in the present embodiment, a downward acceleration of 1 g (i.e.under gravitational force) can be achieved without mechanical forcing.In addition, using additional forcing methods, a further acceleration of1 g may be imparted to the collation without resulting in the separationof adjacent sheets. Hence, accumulated collations emerging from theaccumulator 350 of the present embodiment may be accelerated at roughly2 g without resulting in sliding separation of the sheets. This allowsfor faster progression of the accumulated collation through thefolder/inserter 1000, resulting in a higher-volume throughput of sheetpackages.

Referring again to FIGS. 4 and 5, the operation of the accumulationsection will be described in more detail.

As already outlined, as the sheet collation enters the accumulationsection, the individual sheets are engaged by the pair of accumulatordriving belts 351. At the accumulator inlet side, a pair of driverollers 104 (FIG. 5) feeds the sheet material along the sheet feed pathtowards the drive belts 351. The drive belts 351 are stopped whilst thedrive rollers 390 continue to feed a sheet into the accumulator 350.This allows subsequent sheets arriving after the first to be effectivelyoverlapped with the sheet or sheets already in the accumulator 350 toensure that they are engaged by driving means 351 and accumulated in thecorrect order.

According to the present embodiment, there are three methods by which adocument may be fed into and accumulated in the accumulator. The firstis as described above, where individual sheets are fed from the separatefeed trays 1, 2, 3, 4 (FIG. 1), loosely collated in the sheet feedercollation section 100, and then accumulated in the accumulator 350. Inthis mode, the sheets pass directly into the accumulation chamber in thecorrect order because they are already partially overlapped. As such,the second and subsequent sheets are always received between thesheet(s) already present in the accumulator and the traction belts 351,so that they are driven downwardly and accumulated against theaccumulation gate 354 in the correct order.

The folder/inserter may also operate in two further modes for folding amail piece and inserting it into an envelope. According to the secondmethod, pre-stapled sheets, for example a five-page document stapled inone corner, are placed in the convenience tray 200. This document isthen fed directly to the accumulation chamber, where no furtheraccumulation is required owing to the sheets being stapled. The documentthen exits the accumulation chamber and is folded and inserted asnormal.

According to the third method of operation, a plurality of ordered,loose sheets are placed in convenience feeder 200 or one of the sheetfeeder trays 5, 6, 7 or 8 (FIG. 1). These sheets are fed successivelyone-at-a-time along the sheet feed path and into the accumulator.However, in this mode, the sheets are not partially overlapped in thepaper feed path, and this leads to the risk that the sheets will becomeincorrectly ordered, or incorrectly fed into the accumulator, leading tomis-collated mail packages or a jam in the folder/inserter machine 1000.

To overcome this problem, a trail edge deflector 380 is provided (FIGS.1, 5). In the third mode, the trail edge deflector acts to lift thetrail end of a sheet whose lead end is already in the accumulator 350,to thereby ensure that the subsequent sheet to arrive is fed into theaccumulator between the previous sheet and the traction belts 351. Thetrail edge deflector 380 comprises a roller 381 through which there is apassage 382 suitable for allowing one or a plurality of sheets to passthrough the roller. The passage is flared at the inlet and outletthereof to better accept the introduction of a sheet leading edge, toprevent jamming of the folder/inserter 1000.

In the first and second modes the sheet(s) or stapled document(s), etc.simply pass through the passage in the deflector and into theaccumulator.

In the third mode of operation, the sheets arriving individually passpart-way through the passage, and the leading edge of the sheet entersthe accumulator 350 and is contacted by the traction belts 351 to driveit down against the accumulation gate 354. As the trail edge of eachsheet reaches the trail edge deflector, the deflector rotates by 180°(anticlockwise as shown in FIG. 5). This forces the trail edge of thatsheet upwards and it then lies above the trail edge deflector. The inletand outlet of the passage 382 through the trail edge deflector have thenreversed positions and the subsequent sheet enters the passage throughwhat was previously the outlet. This is possible because the passage hasa cross-section with rotational symmetry. The subsequent sheet is thenguaranteed to be fed into the accumulator underneath the trail edge thatwas previously deflected, i.e. between the previous sheet and thetraction belts.

This third mode of operation is particularly useful when, for example, adocument has been printed by a laser jet printer and is collated in thecorrect order, and it is not desired to have to sort the individualpages of the document into the appropriate individual sheet feed trays.

After leaving the accumulator, the collation passes into the foldingsection 500 which contains a variable folding apparatus. The operationof such a folding apparatus is known, for example from GB-A-2380157.Brief explanation is given here for a more complete understanding.

Referring to FIG. 6, the folding apparatus comprises four rollers501,502,503 and 504 arranged to form three pairs 510,520 and 530. Theleading edge of the collation passes through the first roller pair 510and into a buckle chute 511 until it reaches an adjustable stop 512,here constituted as a pinch roller pair 513 which selectively stops thecollation based on detection of the leading edge position. At thispoint, the first roller pair continues to feed the sheet collation,causing it to buckle, and causing the buckled portion to enter the nipbetween the second roller pair 520. This results in the buckled portionbeing fed through the second roller pair 520 and forming a fold at thebuckle, at a predetermined position. The folded edge then becomes thelead edge of the collation and it is fed through the second roller pair520 into a second buckle chute 521 until it moves into contact with asecond stop 522 (which is preferably a pinch roller pair 523) whichhalts its movement. The second roller pair 520 continues to feed thetrailing edge of the sheet collation therethrough. Again, this causesthe collation to buckle, and the second buckle is forced into the nip ofthe third roller pair 530, resulting in a second fold in the sheetcollation at a predetermined point in the region of the second buckle.

By selectively determining the point at which the sheet collation ishalted by the stops 512,522 at each stage, it is possible to alwaysachieve the folds in the desired position. Further, by appropriatelyselecting the distance from the roller pairs at which the collation ishalted, the same apparatus can selectively perform either a double fold,a “Z” fold or a “C” fold in the sheet collation. Equally, the sheetcollation need only be folded a single time, for example simply foldedin half. This single fold is achieved by operation of a half-foldmechanism 550. If a half-fold operation is selected, the half-foldmechanism 550 moves in the direction of arrow A to an interferenceposition where it intercepts and redirects the accumulated collation asit exits the first roller pair 510. The collation is then directedimmediately through the second roller pair 520, rather than into thefirst buckle chute 511. Accordingly, the first fold is never made in thecollation at the nip of the second roller pair, and only a single foldis created as the collation is buckled in the second buckle chute 521and the buckle passes through the third roller pair 530, as normal.

Referring again to FIG. 1, after the final fold is made, one or moreinserts may be fed from insert feeders 401 and 402 shown on the righthand side of FIG. 1. The present embodiment has two insert feeders 401and 402, which both feed an insert into and along an insert feed path.One or both inserts are then collated in the insert feeder collationsection 450 and the collated inserts are held at insert staging area Iwhilst the sheets are folded. These collated inserts are then fed intothe final fold in the sheet collation and form part of the foldeddocument. Typically, these inserts might be booklets, business replyenvelopes, compliment slips, product samples, etc. of varied shape,size, thickness and pliability.

Below the sheet feeders 1 to 4 is located the envelope feeder 600. Thisholds a plurality of envelopes in a stack, and has an associatedmechanism for removing the single uppermost envelope from the stack andfeeding said envelope along the envelope transport path 650. Theenvelope first undergoes a flapping process in flapper section 700, inwhich the flap is opened. The envelope is then held in the insertionregion 750, where it is stopped. Mechanical fingers engage with and holdopen the mouth of the envelope. In this state, the folded mail collation(including inserts) is inserted into the envelope by projecting the mailpackage towards the open mouth with sufficient velocity that itsmomentum will force it inside the envelope. This mail piece, comprisingthe folded mail package within the envelope, then proceeds to thesealing and ejection section 800. In the sealing and ejection sectionthere is a moistening device 820 where the gum seal on the envelope flapis moistened. The envelope is then passed through a sealing/ejectionmechanism 840. This performs a process which shuts and seals themoistened flap and ejects the envelope from the folder/inserterapparatus 1000 into a receiving tray or bin.

According to the above description, as the sheet collation enters theaccumulation section, the individual sheets are engaged by theaccumulator driving means 351. In the present embodiment, thisaccumulator driving means takes the form of a pair of traction belts. Inthe paper feed path there are sheet feed path driving means 104 feedingthe sheet material along the sheet feed path towards the accumulatordriving means 351. Regardless of the form of the sheet material—whetherit be a partially overlapped collation (as described above), a pluralityof single sheets in succession or a stapled pamphlet—it is necessary toaccurately match the “feeding speed” of the sheet feed path drivingmeans 104 with the “receiving speed” of the accumulator driving means351. Referring to FIG. 7, there is shown a speed-matching mechanism 900for accurately matching the feed rates of the sheet feed path drivingmeans 104 and the accumulator driving belts 351, shown schematically inFIG. 7, under control of a system controller 907. Simple speed-matchingcan be achieved by mechanical interaction—i.e. via a system of gears ora chain and sprocket connection linking the two driving means andforcing them to produce a matched feed rate. However, in order for theaccumulator 350 to function properly, it is necessary to be able to stopthe accumulator driving means 351 whilst continuing to drive sheetmaterial into the accumulator with the sheet feed path driving means104. This is necessary to enable the accumulator driving means 351 to behalted by the drive controller 907 whilst a subsequent sheet is fed intothe accumulator in the correct order, thereby creating or increasing anoverlap between adjacent sheets.

The mechanism 900 of the present embodiment concerns two coupledrotational driving systems—one comprising traction belts 351 of theaccumulator and the other comprising the drive rollers 104 on the sheetfeed path. Each driving system comprises a respective motor, i.e. afeeding motor 901 connected via a rotational shaft 902 to the driverollers 104 and a receiving motor 903 connected via a second rotationalshaft 904 to the drive roller of the accumulator driving means 351. Bothmotors are controlled by a system controller 907. The rotational shaftsof the two motors 901,903 are linked by a drive belt 905 which rotateswith the rotational shaft 902 of the feeding motor 901. The drive belt905 is coupled to the rotational shaft 904 of the receiving motor 903via an overrun clutch 906. This allows the feeding motor 901 to turnwhilst the receiving motor 903 remains stationary. However, when it isdesired to feed a sheet by means of the drive belt 351 of theaccumulator, the receiving motor 903 begins to rotate. The motors may becontrolled such that the receiving motor 903 will be driven at higherpower than the feeding motor 901, thereby ensuring that the feedingmotor 901 does not “overtake” the receiving motor 903. The feeding motor901 may be unpowered in this phase, but it is preferred that it shouldbe powered in order to distribute the load required to drive the sheetmaterial between the two motors. Using the arrangement described, it ispossible to hold the accumulator receiving motor 903 stationary whilstthe feeding roller 104 drives a sheet into overlapping arrangement withanother sheet held static in the accumulator 350. When the accumulatordriving motor 903 is activated, and both motors are runningsimultaneously, the sheets will not stretch or become buckled since thesheet will be fed at precisely the same feed rate by both the sheet feedroller 104 and the accumulator drive belts 351.

Thus, two independent drive systems are provided, each consisting of: amotor driving a roller set, via a combination of shafts, pulleys, beltsand/or gears. Both motors have speed control systems and can be drivenindependently via a machine controller 907. The two drives are thenlinked via belts and pulleys and/or gears, with one of them linked to anoverrun clutch. This clutch is set up such that when only motor 903 isdriven in the direction of paper travel, both the feeding and receivingrollers will turn. However, if only motor 901 is driven in the directionof paper travel, only the feeding roller will turn. The method ofoperation is then: motor 901 is powered and turns the “feed rollers”;this drives a sheet of paper towards the “receiving rollers”. As thepaper approaches, motor 903 is powered and controlled to drive at thechosen speed. Motor 901 power may be reduced to ensure that, although itassists in the driving, it does not overtake motor 903, or power may beremoved from motor 901. The “feed rollers” turn until the sheet haspassed, and the motors are then stopped. With the arrival of the nextsheet, motor 901 starts again, turning just the “feed rollers” toadvance a second sheet of paper. This sheet is transported towards the“receiving rollers” and the awaiting first sheet which remainsstationary, thus enabling the two sheets to be overlapped.

Thus, semi-independent drive of two separate drive systems can beprovided such that the feeding roller can be driven forward withoutaffecting the receiving roller. The use of a mechanical linkincorporating an overrun clutch means that if the receiving roller isdriven, the feed roller will also be driven at a speed defined by thegear/pulley ratios. Optionally, motor 901 can still be driven at thistime, in order to take some of the load, as long as the power is notsufficient for it to overtake motor 903.

The exact drive train from each motor to its respective roller isunimportant, and the motors may be linked to the roller drive shaft by aseries of gears, belts and pulleys, if desired. The overrun clutch can,instead, be put on the motor 901 drive shaft, but it must be mounted inreverse so that it performs the same function.

The clutched link introduces very few additional components, all of alow cost. The use of this clutch ensures that the speed is veryaccurately matched through the gear ratios without resorting to complexcontrol systems with precision feedback. There is also no use ofexpensive electromechanical clutches with the associated risk of wearand failure that these can entail.

Importantly, although the feeding speeds of the feeding rollers andreceiving rollers may be matched exactly, it is often desirable to havethe two roller sets linked so as to be driven having a predeterminedspecific ratio between their feeding speeds. It may, for example, bedesirable to set the feeding speed of the feeding rollers slightlyhigher than the feeding speed of the receiving rollers in order toensure that a buckle is normally formed in the sheet, in order toaccount for tolerances in roller diameter/feeding speed due to wear,manufacturing defects, etc.

Moreover, although it is necessary that the feed rollers 104 should bedrivable independently of the receiving roller and belts 351, it is notabsolutely necessary to employ two separate drive motors if suitableselectable drive chains and/or clutches are coupled to a single motor.

1. A sheet handling apparatus comprising: a first sheet feeding meansfor advancing a sheet along a sheet path; a second sheet feeding meansfor feeding the sheet along a continuation of the sheet path; fordriving the first sheet feeding means independently of the second sheetfeeding means and for common drive of the first and second sheet feedingmeans; and a drive controller arranged to control said driving means toenable a sheet to be driven along the sheet path from the first sheetfeeding means to the second sheet feeding means whilst the second sheetfeeding means remains undriven and to enable continued feeding of thesheet by both sheet feeding means.
 2. The sheet handling apparatusaccording to claim 1, wherein for said common drive, the feeding speedof the first feeding means is set at a specific ratio with respect tothe feeding speed of the second feeding means
 3. The sheet handlingapparatus according to claim 1, wherein for said common drive thefeeding speed of the first feeding means is matched with the feedingspeed of the second feeding means.
 4. The sheet handling apparatusaccording to claim 1, wherein the second sheet feeding means isstationary when undriven.
 5. The sheet handling apparatus according toclaim 2, wherein the second sheet feeding means is stationary whenundriven.
 6. The sheet handling apparatus according to claim 1, whereinthe first sheet feeding means comprises a feed roller.
 7. The sheethandling apparatus according to claim 6, wherein the second sheetfeeding means comprises one or both of a feed roller and a tractionbelt.
 8. The sheet handling device according to claim 1, wherein thedriving means comprises: a first motor coupled to the first feedingmeans; a second motor coupled to the second feeding means; and acoupling arrangement for selectively coupling the second motor to thefirst feeding means.
 9. The sheet handling apparatus according to claim8, wherein the coupling arrangement is a series of gears, havingappropriate ratios to set the relative feeding speeds of the first andsecond feeding means.
 10. The sheet handling apparatus according toclaim 9, wherein the coupling arrangement comprises: a feeding gearconnected to moving parts of the first feeding means; a receiving gearconnected to moving parts of the second driving means; and a belt orchain passing around both gears and constraining the feeding gear torotate in synchronism with the receiving gear.
 11. The sheet handlingdevice according to claim 8 wherein the coupling arrangement comprises aselectively operable clutch.
 12. The sheet handling device according toclaim 9 wherein the coupling arrangement comprises a selectivelyoperable clutch.
 13. The sheet handling device according to claim 8wherein the coupling arrangement comprises a selectively operableclutch.
 14. The sheet handling device according to claim 13 wherein saidclutch is a one-way clutch.
 15. The sheet handling device according toclaim 1, wherein the second sheet feeding means forms part of anaccumulation apparatus for accumulating a plurality of sheets fed to theaccumulation apparatus by the first sheet feeding means.
 16. A method offeeding sheets in which a sheet is fed by first feeding means to asecond feeding means whilst the second driving means remains undrivenand the sheet is further advanced by both the first and second feedingmeans set at a specific ratio therebetween.
 17. A method according toclaim 16, in which the first and second feeding means are driven byrespective drive shafts which are coupled together by means of aselectively operable coupling arrangement.
 18. A method according toclaim 16, in which the speeds of the first and second feeding means arematched.
 19. A method according to claim 17 in which the speeds of thefirst and second feeding means are matched.